Limit-switch mechanism



y 1, 952. N. E. ANDERSON 2,602,124

' LIMIT-SWITCH MECHANISM Filed July 1, 1950 3 Sheets-Sheet l INVENTOR NELSON E.ANDERSON J y'L 1952 N. E. ANDERSON LIMIT-SWITCH MECHANISM 3 Shee ts-Sheet 2 Filed July 1, 1950 24(lower Iimir switch) INVENTOR v NELSON E.ANDERSON BY :2 4, AZ Z2.

ATTORNEYS July 1952 i N. E. ANDERSON 2,602,124 LIMIT-SWITCH MECHANISM Filed July 1, 1950 3 Sheets-Sheet s INVENTOR NELSON E. ANDERSON 7, LJg L'a v Q ATTORNEYS Patented July 1, 1952 UNITED (STATE PATENT o-Fr cE LIMIT-SWITCH MECHANISM I Nelson E. Anderson,Berkeley Heights, I, assignorto Air Reduction Company, Incorporated, New York, N. Y a corporation of New York Y I Application July 1, 1950,

' solaims- (oi.'ze9 -i7) direction, it is frequently desirable to mount the limit switch so that its position jmay'beadjusted to vary the point in the travel of the motor- -driven part-fat which the limit switch will be actuated to arrest'its motion. Ordinarily the position of such alimit switch could not be adjusted to cause a shorter movement of the motordriven part if'the motor-driven part happens to be in the position-it assumes when its motion has just been arrested by the limit switch because eel-a1 No. 171,625

.which engages. with Pit /Experience has shown I travel between welds.

; has reached the that in; weldingfapparatus ofthis kind only one limit for the motor-produced upward movement of the electrode holder is insuilicient for practical purposes because under many working conditions it is not necessary tor the electrode holder to be raised to the extremelimit of its upward Itlis not always. convenient to manually operate a switch to. stop the up ward= mcvement ofsthe electrode holder, when it desired elevation short of the eX- treme 1imitof its upward movement especially when its retracting action or upward movement takes place automatically when the welding current is shut off; To allowthe electrodeholderto be raised by its motor to the extreme limit of its-upward movement and then subsequently then the limit switch is held against movement in the direction in which it should'b'e adjusted to effect a shorter movement of the motor-driven part.

The principal, object or this invention is to provide anadjustable limit switchand manually operable means for adjusting it such that even if the motor-driven part happens-to be in the position just mentioned. the manually operable means for adjusting the limitswitch may be preset and this will cause the limit switch, as soon as it is free to do so during the return movement of the motor-driven part, to, assume an adjusted position such that it will thenarrest desirednew -point in its travel. I 1 My improved limit switch mechanism was dethe movement of the motor-driven part at the signed primarilyior use inconnection with electric welding apparatus of the-type by which solower it to the desired level is time consuming and a roundabout way of accomplishing the desired result.

" According to the invention-when applied to electric welding apparatus of the kind abovereierred to, the upper limit switchis mounted so that its positionmay be adjusted to vary'the point inthe upward travel of the electrode holder at which the limit switchwillb'e actuated to arrest manually operable adjusting to the. limit'switch in such the electrode. holders upward movement,- and meansis connected away that even if the parts are, in the position they assume when the upper limit switch has just been actuated to arrest the upward movement of the electrode holder (and the limit switch is therefore held against movemeritin a direction which would bring about a shorter upward movement-of'the electrode holder) the-manually operable adjusting means canyneverthelesabe preset to cause I the, upper limit switch to assume some newadj'usted position (determined by the setting of the called mechanicalwelding can be performed, and

in electrical apparatus of other kinds.

Electric welding apparatus of the kind for which the improved limit switch mechanism was especially designed has an electrode holder that is motor driven toward and away from the work, and a pair of limit switches whichprevent the electrode holder from being raised or lowered beyond certain extreme limits usually determined by the mating rangeof the usual rack on the electrode holderand the'motor-driven pinion the invention will be described in its application to that particular type of electrical apparatus' but it should be understood that it may be used I 'manual'adjusting means) as soon as the electrode holder is lowered and thereby renders the upper limit switch .movable in the desired direction.

Thus; the manually "operable adjusting means may be set to bring about the. desired adjustment of the upper limit 'switch'regardless of the posittion" of thefielectrodei'holder at the time the adjusting-means is manually. set. The accompanying drawings illustrate the invention as applied to electric welding apparatus for use in mechanical welding. In-the drawings:

Figure 1 is an end elevation of welding apparatus equipped with limit switch mechanism of the'ki'nd contemplated by the invention;

Fig: 2 is an exploded perspective View of a por- ;uon of'the apparatus .shown in Fig. 1 showing the upper and lower limit switches, their actuating mechanism, and the manually operable adjusting means for the upper limit switch;

Fig. 3 is a right end view of the parts which appear to the left of the line 3-3 of Fig. 2 when in assembled. condition;

Fig. 4 is a sidenelevatiom-partly in. vertical section, of the parts shown in Fig. 2 as they appear when viewed from the rear and when in assembled condition; and

Figs. 5 and 6 are a plan viewzand aleftiend view respectively of the upper .limitswitch and the parts which appear inassociation'with it in Fig. 2.

Referring first to Fig. l, the welding apparatus shown therein includes an electrode holder or welding torch shown at Ill" within which is mounted an electrode l I. The details of the electrode holder are not. important so far as" the present invention is concerned, it being sufficient toLnote .that a:vertically-disposed rackl2 is mounted on' the electrode holderwhich meshes with an actuating'pinion IS on the end of a shaft M. It is evident from this arrangement that the :electrode holder may be adjusted toward or away from thework by rotation of. the shaft l4 in one direction or the other.

' The shaft I 4 is motor'driven and in the-particular welding apparatus illustrated in Fig. l is "driven by the-output of :adifferential l5 which combines the outputs" oftwo electric motors designated lB and [1. Agear reduction unit l8, shaft I9," and-coupling" 20, connect the motor 16 with the differential- I5;andsimilar-mechanism connects motor I"! withthe differential.

The motor mechanism-above described for rotating the shaft ['4 and raising and lowering the electrode holder may be siinilar to, and operate on the same principle as, the motors shown in my Patent No. 2,461,798, issued'February 15, 1949, for automaticallyadjusting the position of the-electrode holder in accordance with'the' arc voltage; In addition, the motor I! may be operated while the motor I6 is at rest to raise the electrode :h'older l0, and" the motor l6 may be operated while-the motor' l! is' at rest to lower the electrode holder, this beingiaccomplished by suitable switches notashownziiiThus; the motors may-be considered as anymotor-means; either a 7 single motor'or two motors, for rotating the shaft 1 ['4 in the proper direction toaraiseor'lower the electrode h'olderz. I 0.

Anidler gear 2| isdriven by .apinion mounted 'on the shaft l4.1".Thisfpinion' doesnotzshow in Fig. "1 becauseit is located in back of 'the'gear 2| but it appears intfsome of rth'et'otherfigures. The idlergear 2 I carries a pin 22 which engages the contaet arm" 23 of alower limit switch 24, or the contact arm- 2'5 ofan'upper limit switch 26. 1 When the: contact arm" 23 oftth'e' lower tlimit switch is moved 'b'y thepin 22the downward movemento'frth'e electrodeholder' l0 is arrested, i and when the contactarnir25' of 'the upper. .limit switch is movd'b'y the 'pin' 22 the upward'move- 'ment' of these'lectrodetholder is arrested. Ordinarily, the limit switches prevent the electrode holder from: being moved reither: up or down heyond the mating'. range ofthe'rack l2'a'nd the pinion l3.

abovestated it isi'desi'rable to make at least the:upper:iimitzswitchiadjustable. so;that when :the electrode? holder is'fb'eing mntort'driven" away from the'workgi. e.;iwhen.it is;b1eing raised, it will ZTJStOPI at: somez'desired .elevationlshort of its ex- :tttreme. limit of upwardImoizement:determinedby 9 I tain the upper*"limit the mating range of the rack and pinion l2l3 and by the normal position of the upper limit switch. The mechanism for accomplishing this is best shown in Figs. 2-6, inclusive.

The idler gear 2| with its pin 22 that constitutes the actuating element for the limit switches and. the lowerand :upper limitswitches 24 and '26, respectively, with their"contact arms 23 and r 25, are more clearly shown in Fig. 2, which is an exploded perspective view of a part of the T'Tmechanism illustrated in Fig. 1. Fig. 2 also clearly shows at 27 the above-mentioned pinion on-the shaft M which drives the idler gear 2!. .1 Referrin'gu'fdrther to Fig. 2, the lower limit 1 switch 24 isisecured to a fixed part 28 of the machine but the upper limit switch 26 is carried bylaiibracketi29, the arms 30 and 3| of which are mountecl on an adjusting shaft 32 so that thesearms and the limit switch itself may be moved about the axis of the adjusting shaft. *When-the"parts shown iii Fig. 2 are in assembledrlationtlii-idler gear 21 rotates-freely on the adjusting-shaft and the pin 22 moves in -an arcuate pathi The1cbntact arm' of the up- 5 per'limit'switcli 26 lies iii-the path of movement or the pin 22' so-that'wheh the'electrode holder is being raised the pin 22, now rotating in a clockwis direction 'as-viewed in Fig. 2, will eventuallycontact 'with' the under surface of the contact -arm 25 andmove thisarm to open the upper limit switch and thereby arrest'the upward movement of the-electrode holder. In Fig. 2thelpin 22 is 'shown iii-about the position it assumes 'when it 'contacts with the contact arm 25 5- of the upper limit switch. Similarly the contact 1 arm 23 of th'e' lower limit switch 24 lies in the path o'fimovement of theipin' 22 so that when F r-the electrode holder isi-beinglowered and the pin; 22 is-moving in tavcounterclockwise direction, 46 as view'ed in: Fig. 2 ,t -thepin wil1 engage this conf :tactarm' tolmove it and' operate the limit switch 2*; 24: and: thereby. arrest the: downward movement 1:: of; theielectrode liolder.

A-rcollair33is fixed to thefadjusting shaft 32 4 bet-ween" the arm's Hr-and 3-! of the" limit switch bracket 29. A pin 34 extends radially from this J collarsas bestsho'wn in Fig. 5.1 Acoil spring 35 i is=mounted orf theadjusting' shaft 32' between l the 'bracketarms 3fl'and 31 incoaxial relation gwith the adjustingshaft'. One end of this spring ishooked'over thpin- 34""( Figs. 5 and 6) and the 1 other endis' attached to the'bracketarm 30. The spring iswound up enough when the parts are -"assembled to bias the upper li'mitswitch 26 in 5 a counterclockwisedirection"on' the adjusting "'-sl'iaft'32-'-andmaintain a part of the bracket 29 in'contact'with the pin 34 on the collar 33. Thus, the pin 34 actsas a 'stop' which is engaged by apart on --th'eliinit-= s"witch' to normally mainswitch in 'a normal position'relative to the adjusting shaft 32.

-The adjusting shaft 32 is in axial alignment 'with. a shaft sectioii-32a(Fig. 2) which is keyed to the: adjusting shaftzbymeans of a key and c5 keywayshown at SBZ 'I'heOuter end of the shaft section32aturns in a be'aring member 31 which ".1- is mounted inian' opening"38- in a fixed part 39 i'ilof.the welding' apparatus (see also Fig. 4). The z..';adjusting.iishaftl32 and3 the shaft section 32a t:.t'hereforeiconstitute. in'effect a single adjusting :i:shaft;:the:outer:end oflwhich is rotatively supporteotin: thezsfixeid partf 391 of the welding apii'paratus andgthepther end of which is rot'atively LL: supported inithetfixed part 28 ofthe welding api-ParatusLEitTheLend' of the: shaftfisection 32a has a handle 40 secured to it. This handle also appears in Fig. 1. --A detent mechanism 4| associated with the. shaftsection 32a'yieldingly holds the adjusting shaft in any one of a number ofpositions to which it may be turned by the. handle It will now be seen that if the adjusting shaft 3232a is turned in a clockwise direction by the handle 40 the pin 34 carried by the actuating shaft, being in engagement with the bracket 29, will move the limit switch 2Sbodily about the axis of the adjusting :shaft in a clockwise direction. This will increase the elevation at which the movement of the electrode holder will be arrested during its upward movement because the pin 22 will then contact with the contact arm 25 of the upper limit switch later in the upward movement of the electrode holder. Whenever the upper limit switch 26 is free to move in a counterclockwise direction about the axis of the adjusting shaft 3232a, as when the pin 22 is not in contact with the under surface of the contact arm 25, turning of the adjusting shaft 32- 32a in a counterclockwise direction by the handle 40 will also cause the limitswitch' 28'to move in a counterclockwise direction aboutthe axis of the adjusting shaft because the bracket 29 of the upper limit switch is yieldingly retained in contact with the pin 34 by means of the coil spring 35. 22 to come in contact with the under surface of the contact arm 25 of the upper limit switch earlier during the upward movement of the electrode holder and thereby arrest. its'movement at a lower elevation. happens to be in a position in which the pin 22 is in engagement with the under surface of the contact arm 25 of the upper limit switch then this limit switch cannot be moved in a counterclockwise direction about the axis of the adjusting shaft, but the pin 34, and the part of the upper limit switch with which. it cooperates, constitute a one-way coupling so that, even un- This adjustment will cause the pin If the electrode holder 2 der these circumstances, the adjusting shaft can be turned by the handle 40' in a counterclockwise direction to some desired position whilethe limit switch 26 remains stationary, andthen when this limit switch is free to do so, i. e., during the first part of the downward movementof the electrode holder, the limit switch will be moved by the coil spring 35 (now wound even tighter by the turning of the adjusting shaft while the limit switch remains stationary)" in a counterclockwise direction until the bracket 29 again contacts with the pin 34. 'fThus, if it is desired to adjust the upper limit clockwise direction about the axis of the adjusting shaft when the pin 22 holds this limit switch against such counterclockwise movement, the adjusting shaft can be turned in a counterclockwise direction and preset at some position corresponding to the desired adjustment of the limit switch. Then when the limit switch is free to do so it will move to the desired adjusted position depending upon the presetting of the adjusting shaft. I I

The adjusting shaft can therefore be turned at any time to effect the desired adjustment of the position of the upper limit switch regardless of the position in which the electrode holder happens to be at the time.

The invention is applicable to any limit switch, whether it be an upper limit switch or a lower limit switch, and if desired, each one of a pluralswitch 26 in a 'counterity of limit switches may have adjusting means of the kind described. The above-described l. Limit-switch mechanism for limiting the movement of a motor-driven part comprising a limit switch mounted so that its position may be L adjusted, an actuating element for the limit switch which moves in accordance with the movement of the motor-drivenpart, the limit switch having an arm located in the path of travel of said actuating element and adapted when moved thereby to operate the limit switch, and manually operable means for adjusting the position or the limit switch comprising an adjusting member movable in opposite directions; a one-way coupling between said member and the limit switch comprising a stop portionon the adjusting member normally engaging a stop portion on the limit switch, and a spring interposed between a part on the limit switch and a part on said adjusting member and biasing the limit switch to a normal position relative to the adjusting member in which said stop portions are in engagement, said stop portions being so arranged that'when the limit switch is held against movement in one direction by the actuating. element, and the adjusting member is moved to a selected position in a direction that will move its stop portion in the direction in which the limit switch cannot move,

the stop portion on the adjusting member will move away from the one on the limit switch and the spring will then function when the limit switch is free to move itto said normalposition in which thestop portions are againin engagement but when th'e'adjusting member is moved in the opposite direction the stop. portions will remain in engagement and the movement of the adjusting member will be positively transmitted to the limit switch through the one-way coupling.

2. Limit-switch mechanism for limiting the movement of a motor-driven part comprising a limit switch mountedso that it is bodilyadjustable in position, an actuating element .iorithe limit switch which moves in accordance with the movement of the motor-driven part, the limit switch having an arm located in the path of travel of said actuating element and adapted when moved thereby to operate the limit switch, means for adjusting. the position of the limit switch comprising an adjusting member movable in opposite directions, a one-way coupling between said member and the limit switch comprising a stop carried by said adjusting member normally engaging a part on the limitswitch, a spring biasing the limit switch to a normal position relative to the adjusting member in which said part on'the limit switch is in. engagement with said stop on the adjusting member, and manually operable means for moving said adjusting member, said stop on the adjusting member and the engaging part'on the limit switch being so arranged that when the limit switch is held against movement in one direction by the actuating element, and the adjusting member is moved to a selected position in a direction that will move its stop in the direction in which the limit switch cannot move, the stop on the adjusting member- 7 will move away from the engaging part on the limit switch and the spring will then function when the limit switch is free .tomove to moveit to said normal position in which the-stopon the adjusting member is again in engagement with said part on the limitswitch but when the adjusting member is moved in the opposite direction the stop on the adjusting member and said part on the limit switch will remain in engagement and the movement of the adjusting member will be positively transmitted to the limit switch through. the one-way coupling.

3. Limit-switch mechanism for limiting the movement of a motor-driven part comprising a limit switch, a movable shaft, means mounting the limit switch on said shaft for limited bodily movement relative to the shaft, an actuating element for the limitswitch which moves in accordance with the movement of the motor-driven part, the limit switch having an arm located in the path of travel of said actuating element and adapted when moved thereby to operate the limit switch, a one-way coupling between said shaft and the limit switch comprisinga stop carried by the shaft normally engaging apart on the limit switch, a spring biasing the limit switch to a normal position relative to said shaft in which said part on the limit switch is in engagement with said stop on the shaft, and manually operable means for moving the shaft, said stop on the shaft and the engaging part on the limit switch being so arranged that when the limit switch is held against movement in one direction by the actuating element, and the shaft is moved to a selected position in a direction that will move its stop in the direction in which the limit switch cannot move, the stop on the shaft will move away from the engaging part on the limit switch and the spring will then function when the limit switch is free to move to move it to said normal position in which the stop on the shaft is again in engagement with said part on the limit switch but when the shaft is moved in the opposite direction the stop on the shaft and said part on the limit switch will remain in engagement and the movement of the .shaft will be positively transmitted to the limit switch through the oneway coupling.

4. Limit-switch mechanism for limiting the movement of a motor-drivenpart comprising an 4 adjustable limit switch, a rotatable adjusting shaft, means mounting the limit switch on said shaft for limited bodily movement relative to the shaft and about the axis thereof, an actuating element for the limit switch which moves in ac- 4 cordance with the movement of the motor-driven part, the limit switch having an arm located to one side of said shaft in the path of travel of said actuating element and adapted when moved by said element to operate the limit switch, a oneway coupling between said shaft and the limit switch comprising a stop carried by the shaft normally engaging a part on the limit switch, a coil spring coaxially mounted on the shaft and biasing the limit switch to a normal position relative to the shaft in which said part on the limit switch is in engagement with the stop on the shaft, and manually operable means for rotating said shaft, said stop on the shaft and the engagingparton the Jli'mitaswitch being so arranged that-when the limit' switchis heldagainst movementin one direction by the actuating element, and the shaftis rotated to a selected position in a direction that will move its stop in the direction in which the limit switch cannot move, the stop on the shaft will move away from the engaging part on the limit switch and the spring will then function when the limit switch is free to move to move it to said normal position in which the stop on the shaft is again in engagement with said part on the limit switch but when the shaft is rotated in the opposite direction the stop on the shaft and said part on the limit switch will remain in engagement and the rotation of the shaft will be positively transmitted to the limit switch through'the one-way coupling.

5. Limit-switch mechanism for limiting the movement of a motor-driven part comprising an adjustable limit switch, a rotatable adjusting shaft, means mounting the limit switch on said shaft for limited bodily movement relative to the shaft and about the axis thereof, an actuating element for the limit switch, means for moving said actuating element in co-relation with the movement of the motor-driven part and in an arcuate path concentric with said rotatable adjusting shaft, the limit switch having an arm located to one side of said shaft in the path of travel of said actuating element and adapted when moved by said element to operate the limit switch, a one-Way coupling between said shaft and the 'limit' switch comprising a stop carried by the shaft normally engaging a part on the limit switch, a coil spring coaxially mounted on the shaft and biasing the limit switch to a normal position relative to the shaft in which said part on the limit switch is in engagement with the stop on the shaft, and manually operable means for rotating said shaft, said stop on the shaft and the engaging part on the limit switch being so arranged that when the limit switch is held against movement in one direction by the actuating element, and the shaft is rotated to a selected position in a direction that will move its stop in the direction .in which the limit switch cannot move, the stop on the shaft will move away from the engaging part on the limit switch and the spring will then function when the limit switch is free to move to move it to said normal position in which the stop on the shaft is again in engagement with said part on the limit switch but when the shaft is rotated in the opposite direction the stop on the shaft and said part on the limit switch will remain in engagement and the rotation of the shaft will be positively transmitted to the limit switch through the one-way coupling.

NELSON E. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,760,145 Kent May 27, 1930 2,338,365 Thorp et a1. Jan. 4, 1944 2,474,945 Johnson July 5, 1949 

